The present invention relates to irradiation devices for controlling airborne micro-organisms and, in particular, to a quick-install germicidal irradiation unit for destroying micro-organisms collected on a surface irradiated by the unit.
The airborne transmission of disease organisms, especially respiratory disease organisms, has long been recognized as a serious problem. Health care authorities and biologists have now become acutely aware of the problem due to the evolution of antibiotic resistant strains of streptococcus and tuberculosis, for example. It is well known that many diseases caused by both bacteria and viruses are primarily transmitted from host to host by air currents. Therefore, germicidal air filters have been invented and have proven to be effective in removing microorganisms from the air and destroying them. Examples of such filters are described in U.S. Pat. No. 5,330,722 which issued on Jul. 19, 1994 to Pick and has subsequently been assigned to the applicant. The germicidal air filtration systems described in that patent are principally suitable for permanent or semi-permanent installations.
As another example, a portable germicidal air filter is described in U.S. Pat. No. 5,837,207, which issued on Nov. 17, 1998 to Summers and also assigned to the applicant. The light weight portable germicidal air filter for home and personal use described in that patent includes a cabinet that houses an electrostatic air filter, an ultraviolet lamp and a parabolic reflector or a convex lens for focusing the ultraviolet radiation emitted by the lamp on an upstream side of the air filter. The reflector or the lamp with the lens is constantly oscillated to systematically sweep the upstream side of the filter with germicidal levels of radiation. A fan adjacent the downstream side of the filter draws air through the filter and impels it out through air outlets in the side walls of the cabinet.
It is also known to install stationary unshielded ultraviolet lamps in air ducts of commercial and domestic heating systems, as taught, for example, in U.S. Pat. No. 5,894,130, which issued to Bach on Aug. 13, 1999. Such devices are installed downstream of air filters on the theory that short, high-intensity exposure to ultraviolet light as air is drawn past the ultraviolet lamps will destroy at least a proportion of the microorganisms suspended in the air. A principal disadvantage of such systems is that the unshielded lamps readily collect airborne dust, which rapidly reduces their effectiveness. A further disadvantage is that as velocity of air flow changes due to various operating stages of the air handling system, the efficacy of the treatment changes. Another disadvantage is that areas known to support the reproduction of micro-organisms, such as air filters and air conditioning coils are untreated.
Air handling systems without germicidal radiation are still widely used in many applications. For example, most domestic forced-air heating systems have a filter pad installed in the return air path to remove suspended particulate matter from the air. Micro-organisms on the particulate matter collected on the filter pad are not destroyed and may, in fact, reproduce. A proportion of the particulate matter collected on the filter pad is re-suspended in air when the filter pad is replaced, releasing the micro-organisms again. Studies have also shown that the filter pads are not the only place that supports the growth and reproduction of micro-organisms. A warm and moist environment such as air conditioning and refrigerator coils and ducts surrounding such coils are known to provide a suitable environment for many types of micro-organisms, including fungus and mold.
Therefore, there exists a need for a quick-install irradiation unit adapted to be conveniently installed in proximity to a surface that collects or supports growth of micro-organisms, to expose that surface to germicidal levels of radiation.
It is an object of the invention to provide a quick-install irradiation unit for irradiating a surface.
It is another object of the invention to provide a quick-install irradiation unit that is adapted to be quickly and conveniently installed in proximity to a surface to be irradiated, regardless of an installed orientation of the unit.
It is a further object of the invention to provide a quick-install irradiation unit that is simple to construct, inexpensive to manufacture and easy to install.
These and other objects of the invention are realized in a quick-install irradiation unit for irradiating a surface, which comprises at least one radiation source and means for focusing radiation emitted by the source. A generally elongated support frame is provided for operatively securing the radiation source and means for focusing, to form a quick-install unit adapted to be mountable at only one end thereof. A mounting bracket is provided for mounting the one end of the germicidal unit in proximity to the surface so that the field is coincident with the surface and the surface is exposed to radiation.
The quick-install irradiation unit in accordance with the invention preferably comprises a support structure including an elongated frame and a housing secured to one end of the frame. A mounting bracket adapted to be mounted to a structure supporting the surface to be irradiated receives the housing. The mounting bracket supports the elongated frame in proximity to the surface. At least one ultraviolet radiation source is supported by the elongated frame for exposing at least a portion of the surface to the ultraviolet radiation. If the means for focusing the ultraviolet radiation emitted by the source focuses the radiation in a narrow, concentrated band, it is supported on opposite ends of the elongated frame, and rotatable about the source so that a predefined area of the surface is exposed to the focused ultraviolet radiation at any given time. The focusing means is oscillated by a motor supported within the housing and operatively connected to the rotatable means for focusing, so that the surface is systematically exposed to radiation. The germicidal irradiation unit further comprises means for detachably locking the housing to the mounting bracket.
The focusing of the ultraviolet radiation may be accomplished by a reflector positioned behind an ultraviolet lamp. The reflector is shaped to focus the radiation emitted by the radiation source on a predetermined area. If the reflector is mounted in a stationary position, the reflector is shaped to focus the radiation on the entire area. If, however, the reflector is rotatably mounted, it is preferably shaped to focus the radiation in a narrow, concentrated band on the surface to be irradiated. Alternatively, the radiation may be focused by a reflector behind the lamp in combination with an elongated lens positioned in front of the lamp, so that substantially all of the ultraviolet radiation emitted by the ultraviolet source is focused in a relatively narrow, elongated band on the surface to be irradiated. The means for focusing the radiation, e.g. a reflector or elongated lens, may be oscillated about an axis parallel to the axis of the radiation source by an electric motor, for example, which drives a cam shaft assembly at a predefined rate to effect the desired irradiation of the surface.
The germicidal irradiation unit in accordance with the invention includes very few components and the components are light in weight, and the unit is equipped with a separable mounting bracket. The germicidal irradiation unit is therefore easily handled, and may be quickly and conveniently installed, for example, in an air filter or a heating system to irradiate a filter pad, or any other supporting structures in a desired orientation and proximity to a surface to be irradiated.